Hi Andersg,
The key really to you gaining muscle is to stimulate it first through resistance training.
If you're new to training, and have not used weight before I would personally advice striving for a balanced
diet, with good lean protein sources (meat, fish, nuts, dairy etc).
Aim to get sufficient
calories and see how you get on with that.
If your new to training, the first months are where you can make the biggest gains.
Ensure a combination of wholegrains and complex carbs, good healthy fats from sources such as olive oil and oily fish and lean protein sources.
Focus on getting stronger in the
gym, using compound (multi joint
exercises) and you should do well without the need for any
supplements.
If you really are set on
supplements, then a good whey protein could be used immediately post workout to be eaten with some carbs like banana's, jam sandwiches etc.
Hope that helps